Cannula and sizing insertion method

ABSTRACT

A relatively inexpensive cannula is sized by including indica on a cannulated dilator that is used to measure the depth of a body cavity, and in one embodiment with the use of a cuttable fixture inserted into an initially enlarged dilator retractor made from a cuttable material the excess of the dilator retractor is snipped by a commercial cutter. A tool engaging the end of the cannulated dilator provides leverage on the cannulated dilator for rotation as it is forced into the body cavity, a pusher tool provides leverage on the dilator retractor for inserting the dilator retractor into the body cavity. A clamp that fits the top of the dilator retractor serves to support the dilator retractor through an arm to a rigid structure. In an alternate embodiment one of a series of sized dilator retractors are selected commensurate with the measurement attained by the scaled cannulated dilator.

More than one reissue application has been filed for the reissue of U.S.Pat. No. 6,159,179. The other reissue application is Reissue applicationSer. No. 10/165,991 filed on Jun. 10, 2002. This application is acontinuation reissue of U.S. application Ser. No. 10/165,991, now U.S.Pat. No. Re. 42,525.

TECHNICAL FIELD

This invention relates to a cannula and cannulated dilator and moreparticularly to a cannula intended to be utilized in surgery on apatient which cannula is sized by the measurement obtained from thecannulated dilator for obtaining a desired length of the cannulainserted into the body cavity of the patient for ease of the surgicalprocedure being preformed by the surgeon and the apparatus for insertionof the cannulated dilator and the dilator retractor into the bodycavity.

BACKGROUND OF THE INVENTION

As is known in the medical field, the cannula is utilized for creating apassage extending from the exterior into a cavity in the patient to aparticular location where the surgical procedure is to be performed. Forexample, in current day practices lumbar discectomy whose objective isto decompress the affected nerve root, endoscopic and micro endoscopictechniques are often used. These techniques are becoming popularinasmuch as the patient benefits from the small incision, limited tissuedisruption, better visualization and illumination all of which shortensthe hospital stay and hastens recovery. One of the techniques forperforming the lumbar discectomy is the use of tubular retractor (aspecific cannula) which allows for laminotomy, deical facetectomy,foraminotomy, nerve root retraction and disectomy. A typical procedureis to advance a guidewire through a small incision which is advanced tothe inferior edge of the superior lamina. A small incision is then madethat extends either cranially or caudally. A calnulated cannulateddilator is then inserted over the guidewire. Larger diameter cannulateddilators are sequentially inserted over each other to increase theopening into the body cavity. Typically the guide wire is removed afterthe first cannulated dilators installed and eventually the cannulateddilators are all removed after the, tubular retractor has been insertedover the largest of the cannulated dilators. Once these procedures areaccomplished, the tubular retractor is locked into position by aretractor clamp that is clamped to a retractor clamping arm which isfixed to a rigid member such as the operating table. This provides anunencumbered zone where the surgeon can perform the medical procedurethat was intended to be performed.

As is well known in this field of technology, the cannulated dilatorsand tubular retractors are made from surgical metal material and aresized for the largest depth that is anticipated in the surgicalprocedure. Hence, whether the depth is 10 millimeters (mm), 20 mm, 30mm, etc. Measured from the exterior of the cavity to the most interiorposition in the cavity (inferior edge of the superior lamina) thetubular retractor that may be available for use ii in the surgicalprocedure could be 100 mm or larger. The additional or excess length ofthe dilator retractor is not only cumbersome to use, it is unnecessaryand undesirable.

This invention obviates this problem by providing the necessary elementsthat allow the dilator retractor (cannula) to be cut to size once theincision and diameter of the cavity has been established. Hence, in thesurgical procedure described above the last cannulated dilator in theprocedure in accordance with this invention includes indicia of agraduated vertical scale on the tubular wall, preferably in millimetersthat is viewed by the user. A cannula or dilator retractor, whichbasically is a cylindrical tube made from a plastic or syntheticmaterial in one preferred embodiment or surgical metal in anotherembodiment which is easy to cut and which is transparent in oneembodiment and opaque in another is provided in the largest lengthcontemplated in this particular procedure or alternatively is pro-sizedin a series of sized cannulas. A template that has a diameter that isslightly smaller than the diameter of the dilator retractor made from asoft plastic material such as Teflon material that may include graduatedannular grooves that are graduated vertically in scale that iscommensurate with the indicia scale on the cannulated dilator. Oralternatively, the dilator retractor may also include on the wallindicia corresponding to the indicia on the cannulated dilator. Hence,the surgeon or user merely has to count the annular grooves or theindicia on the wall of the dilator retractor to match the depth of thecavity and with a cutter, cut through the delator retractor which willprovide a cannula that is acceptable to the surgeon without theunnecessary length that has heretofore presented a problem.

An annular retractor clamp is provided to fit over the top of thedilator retractor which obviously is sized to accommodate the width ofthe retractor clamp which, in turn, is utilized to mate with a rigidholder that is clamped to a rigid member such as the operating table orother convenient member to secure the cannula in place.

This invention also contemplates a tool for insertion of the cannulateddilator and a tool for the insertion of the dilator retractor into thebody cavity. The tool for insertion of the cannulated dilator is arectangular shaped planar member that removably fits the cannulateddilator and serves to provide leverage for the surgeon to turn thedilator retractor while it is being inserted into the body cavity toreach its ultimate destination. A tool for insertion of the dilatorretractor is generally a pusher which may be made integral with thetemplate includes an inner bore that is slightly larger than the outerdiameter of the cannulated dilator and includes a flat bottom surfacethat overlies the top end wall surface of the dilator retractor so thatthe pusher provides leverage for the surgeon to slide the dilatorretractor over the scaled cannulated dilator until it reaches the finaldestination in the body cavity.

As an alternate to the use of the cutter and template, it iscontemplated within the scope of this invention, that a series ofdifferent length dilator retractors will be made available so that thesurgeon after making the measurement of the depth of body cavity withthe cannulated dilator will select the dilator retractor that mostclosely matches the size desired.

SUMMARY OF THE INVENTION

An object of this invention is to provide a dilator retractor that issized to fit the patient for use in a surgical procedure.

A feature of this invention is to provide indicia of a vertical scale onthe cannulated dilator to ascertain the depth of the cavity in the bodyin which a medical procedure is to be performed. In one embodiment atemplate made from a relatively soft plastic material fits into thedilator retractor having a scale commensurate with the scale on thecannulated dilator for supporting the dilator retractor as it is cut tothe desired length. In another embodiment the dilator retractor includesindicia on the outer surface that correlates to the indicia on thecannulated dilator. In one embodiment the dilator retractor istransparent, in another embodiment it is opaque, and it can be made fromeither plastic or metallic material when in the opaque embodiments.

Another feature of this invention is the provision of a tool that isadapted to fit the cannulated dilator to allow the surgeon to turn thecannulated dilator as the surgeon pushes the cannulated dilator into thebody cavity against the resistance of the body tissue. In one embodimentthe tool includes concentric bores that define a shoulder that engagesthe end of the cannulated dilator and recesses that engage tabs axiallyextending from the proximate end of the cannulated dilator.

An alternative to the cutting procedure is the provision ofpredetermined different length dilator retractors that permit thesurgeon to select the desire length commensurate with the depth of thebody cavity.

Another feature of this invention is an annular retractor clamp that isslidable over the outer surface of the dilator retractor that is lockedinto place and adaptable to fit onto a flexible arm that is rigidlyconnected to a static structure such as the operating table.

The foregoing and other features of the present invention will becomemore apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view in elevation showing the details of thecannulated dilator of this invention;

FIG. 2 is a perspective view in elevation and section of the cannulateddilator inserted into the cavity of a body and extending to the inferioredge of the superior lamina and a turning tool adapted to retractorclamp onto the tabs extending from the proximate end of the cannulateddilator;

FIG. 2A is a partial view in cross section taken along the lines 2A-2Aof FIG. 2;

FIG. 3 is an exploded view in perspective illustrating the dilatorretractor being fitted onto the graduated template and pusher prior tobeing cut to the desired length;

FIG. 4 is a view in perspective illustrating the dilator retractorfitted onto the template;

FIG. 5 is a view in perspective illustrating the dilator retractor beingcut by a commercially available cutting tool;

FIG. 6 is a view in perspective illustrating the pusher for pushing thedilator retractor into the body cavity;

FIG. 7 is a view in perspective illustrating the pusher and dilatorretractor of FIG. 6 when pushed to the destination;

FIG. 8 is a view in perspective of the dilator retractor and theretractor clamp and the cannulated dilator of this invention;

FIG. 9 is a view in perspective of a series of pre-sized dilatorretractors made from an inexpensive material that as an alternativeembodiment to the cut in situ dilator retractor; and

FIG. 10 is a perspective exploded view similar to FIG. 3 showing anotherembodiment with the grooves in the template removed and the dilatorretractor having indicia on the outer surface.

DETAILED DESCRIPTION OF THE INVENTION

While in the preferred embodiment this invention is being described inconnection with a particular surgical procedure, namely, a lumbardisectomy, it is to be understood that this invention has utility inother types of procedures and as one skilled in this art can appreciate,the invention has particular utility where it is desirable to provide alength of the cannula that is commensurate with the depth of the bodycavity. As used in this patent application the term “cannulated dilator”means a surgical instrument that is utilized to widen the body cavityand the term “dilator retractor” is a cannula intended to fit into thebody cavity. As used throughout this disclosure the term “body cavity”unless indicated otherwise refers to an access hole formed in the bodyof the patient in order to reach the target where the medical procedureis being performed and the term cannula or dilator retractor serves todefine a working cavity or chamber that the surgeon uses to perform amedical procedure. While in the preferred embodiment, it is preferredthat the dilator retractor is made from a plastic material and istransparent as will be appreciated and as will be described herein belowthis invention contemplates a dilator retractor made from metallicmaterial and in certain embodiments the material is opaque.

To best understand this invention reference is being made to FIGS. 1through 8 which shows the cannulated dilator generally illustrated byreference numeral 10 (FIGS. 1, 2, 6, 8), the template and pusher toolinstrument combination generally illustrated by reference numeral 12(FIGS. 3-6), the dilator retractor generally illustrated by referencenumeral 14 (FIGS. 3, 6, 7, 8) and the retractor clamp generallyillustrated by reference numeral 16 (FIG. 8). As best seen in FIG. 1 thecannulated dilator 10 comprises a hollow tubular body 18 typically madefrom surgical metal such as surgical stainless steel, having a beveledend 20 at the distal end of the tubular body 18 and a pair ofcircumferentially spaced tabs 22 extending from the proximate endsurface 24 of the tubular body 18. The beveled at the distal end 20serves to help the insertion of the cannulated retractor 10 entering thebody of the patient and the tabs 22 serve to fit into a tool that thesurgeon utilizes to insert the cannulated dilator 10 as it progressesinto the body until it reaches the inferior edge of the superior laminaas will be described in more detail hereinbelow. It is contemplatedwithin the scope of this invention that other techniques for attachingthe tool to the cannulated dilator 10 could be utilized, as for examplea poly-sided recesses or reversal of the tabs by affixing them to thetool rather than the cannulated dilator and affixing complementaryrecesses in the cannulated dilator and other such techniques could beemployed. What is contemplated by the tool is that it provides leverageto the user so that it allows the cannulated dilator to be turned whileit is being pushed into the body cavity against the resistance of thebody's tissues.

In accordance with this invention, indica 26 is placed on the exteriorof the body 18 and is a graduated scale in millimeters (although anyother unit of measurement can be utilized) that serves to indicate thedepth of the body cavity and is used to determine the length of thedilator retractor 14 as will be described in more detail herein below.The dilator retractor 14 in one embodiment is made from a plasticmaterial that is transparent and is sufficiently strong that exhibitshoop integrity that is capable of withstanding the forces of the tissuetending to exert a lateral force. This provides a relatively inexpensivemember that is capable of being cut while the patient is in theoperating room. In one embodiment the dilator retractor is fitted ontothe fixture—and the fixture includes spaced grooves that are correlatedto the measurement of the depth of the body cavity that is determined bythe indicia of the cannulated dilator 10.

As mentioned above, once the depth of the body cavity as measured by theindicia on the cannulated dilator 10, the dilator retractor 14 is fittedon the scaled end of the template portion 30 which includes a series ofannular grooves that are axially spaced a predetermined distance, say at10 mm, so that the dilator retractor 14 being transparent in thisinstance, once fitted onto the template can be sized. Hence, the usermerely counts the number of grooves that is commensurate with themeasurement taken from the indicia of the cannulated dilator and thedesired length is then cut to the desired length. Obviously, it isimportant that the dilator retractor 14 is initially oversized so thatthe length will be longer than any of the depths of the body cavitycontemplated. Hence, in this manner the cannula is made to fit eachindividual patient. The technique for making the measurement and cuttingto size is described as follows. If the depth of the body cavitymeasurement taken from the cannulated dilator was 30 mm the user wouldcount 3 annular grooves which are spaced 10 mm apart to determine thelength of the dilator retractor desired and would add an addition amountto compensate for the attachment dimension of the annular retractorclamp 18 16. Hence, if the width of the clamp 18 16 is 10 mm and thedepth of cavity is 30 mm, the user would select 40 mm as the juncturewhere the dilator retractor is cut to size.

Once the length of the depth of the body cavity as calculated by thecannulated dilator 10 is determined and while the dilator retractor 14is mounted on the fixture portion 30, and after the user determines thenumber of annular grooves on the fixture portion that will match thedepth of the body cavity as measured by the indicia on the cumulateddilator and the amount necessary to hold the retractor clamp 18 16, theuser with the use of the commercially available cutters 34 snips off theend of the retractor dilator 14. The fixture will also be cut and thissystem for cutting assures that the dilator retractor 14 will have aclean, smooth cut. A suitable cutter 34 is one that is available in manyhardware stores such as Home Depot and is under the name “Orbit”. Thiscutter was tested and has proven to work satisfactory. However, any typeof cutter is contemplated for use with this invention, such ascommercially available knives and pipe cutters, being other examples.

Once the dilator retractor 14 has been cut to size the dilator retractor14 is then fitted over the cannula dilator 10 and is forced into thebody cavity with a suitable pusher tool of the type shown in FIG. 4.Pusher tool portion 36 which in this instance is integral with themember 12 is formed on one end and includes the enlarged diameterportion 38 having a central axial bore that complements the outerdiameter of the cannulated dilator 10. The bottom annular face 40 isformed with a flat surface that bears against the end 42 of the dilatorretractor 14. This serves to provide leverage for the surgeon to pushthe dilator retractor 14 into the body cavity.

Also in accordance with this invention the end clamp 16 comprises anannular body 46 being split at 47 and including a threaded lateral borethat accommodates the tightening screw 50. The central opening isdimensioned to fit over the end of the dilator retractor 14 and slidethereon. Once in position the screw is tightened to secure the clamp tothe dilator retractor 14. A bracket 56 having a bifurcated slot 58serves to engage a flexible arm that is clamped to a rigid member. Thisserves to support the dilator retractor 14 while the surgeon isperforming the surgical procedure.

FIG. 9 exemplifies another embodiment of this invention where thedilator retractors 14 come in a series of different sizes so that thesurgeon after determining the size of the depth of the body cavity asascertained by the graduated scale on the cannulated dilator 10, thesurgeon merely selects the size to match the body cavity depth takinginto consideration the extra length needed to accommodate the clamp 16.

The cannulated retractor tool 39 is a relatively rectangular flat member41 having a central bore 43 that is made from two spaced diameters. Themost inner diameter on the bottom face of the tool 39 is slightly largerthan the outer diameter of the cannula dilator 10 and the outer diameteron the top face of the tool 39 is equivalent to the inner diameter ofthe cannulated dilator 10 to provide a shoulder for bearing on theannular top surface 45 of the cannulated dilator 10. A pair ofconcentrically spaced recesses 49 are formed in the top surfaceextending through the upper portion of tool 40 to accommodate andcomplement the tabs 22. Thus tool 39 serves to provide a leverage toolthat helps the surgeon for forcing the cannulated dilator 10 into thebody cavity and against the resistance created by the body tissueadjacent thereto.

FIG. 10 exemplifies another embodiment of this invention where thefixture 12a which is identical to fixture 12 does not include the spacedannular grooves and the cannula 14a which is identical to the cannula 14includes indicia on the outer wall that corresponds to the indicia onthe cannulated dilator 10. As is apparent from the foregoing the usermerely has to size the cannula 14a by making a measurement of the bodycavity with the cannulated dilator 10 and select the measurementcorresponding thereto from the indicia on the cannula 14a, and after thecannula is inserted onto the fixture 12a, the user cuts the cannula 14aand fixture 12a so that the cannula 14a is sized to fit the body cavity.Obviously, the cannula 14a in this instance need not be transparent andcan be opaque.

What has been described by this invention is a cannula that is sized tofit the individual patient. A cannulated dilator includes indicia of ascale for measuring the depth of the individual patient. With thatmeasurement, the cannula in one embodiment may be made from a plastic,transparent material fits onto a fixture that is cuttable and contains avisible predetermined scale to cut the cannula to the particular length.In another embodiment the cannula includes indicia of a scalecorresponding to the scale on the cannulated dilator and is similarlycut. The invention teaches a tool is provided to insert the cannulateddilator into the cavity and another tool to insert the cannula into thebody cavity. In another embodiment a series of pre-sized cannulas areprovided so that the user can select from this series the size thatcorresponds to the measurement obtained with the cannulated dilator.

Although this invention has been shown and described with respect todetailed embodiments thereof, it will be appreciated and understood bythose skilled in the art that various changes in form and detail thereofmay be made without departing from the spirit and scope of the claimedinvention.

I claim:
 1. A cannulated dilator having an outer surface, saidcannulated dilator for insertion into an access hole formed in a patientfor stretching the tissue adjacent to the access hole so as to enlargethe same, said cannulated dilator having an elongated tubular body, abeveled portion at the distal end thereof, the improvement comprisingindicia on the side outer surface of the cannulated dilator formeasuring the depth of the access hole, said cannulated dilator having aproximal end and a tool engagement portion formed thereon, incombination with a tool having an engagement portion complementing thetool engagement portion of the cannulated dilator adapted to fit thereonfor rotation and applying leverage on said cannulated dilator forinsertion thereof into the access hole and a cannula for fitting intosaid access hole for permitting the performance of a medical procedureafter the cannulated dilator has been removed.
 2. A cannulated dilatorhaving an outer surface, said cannulated dilator for insertion into anaccess hole formed in the body of a patient for stretching the tissueadjacent the access hole and for enlarging the same, said cannulateddilator having an elongated tubular body, a beveled portion at thedistal end thereof, the improvement comprising indicia on the side outersurface of the cannulated dilator for measuring the depth of the accesshole, said cannulated dilator having a pair of circumferentially spacedtabs extending radially from the proximal end, in combination with atool having a rectangularly shaped planar body, a central bore formedintermediate the ends thereof, an enlarged diameter recess extendingfrom one face into said planar body and being concentric with saidcentral bore but spaced from the opposite face thereof to define ashoulder, said tabs complementing recesses formed in said planar bodyadjacent to said enlarged diameter recess, whereby the cannulateddilator fits into said tool and said cannulated dilator engages saidshoulder to permit the user to insert said cannulated dilator into saidaccess hole and rotate same as it progresses into said access hole and acannula for insertion into said access hole to permit a surgicalprocedure after the cannulated dilator has been removed.
 3. Thecombination of a cannulated dilator and a dilator retractor wherein saidcannulated dilator includes indicia for measuring the depth of an accesshole formed in a patient for medical procedure and said dilatorretractor being made from a cuttable material and being dimensionedlarger in length than is anticipated of any depth of said access hole ofthe body of any patient that is anticipated in the medical procedure,the dilator retractor being cuttable commensurate with the depth of saidaccess hole as measured by said cannulated dilator for sizing saiddilator retractor to a length that is shorter than the original lengthof the dilator retractor prior to being inserted into the access hole soas to be utilized for performing the medical procedure whereby saiddilator retractor is sized for the anatomy of the patient.
 4. Thecombination of a cannulated dilator and a dilator retractor as claimedin claim 3 wherein said dilator retractor is made from a plasticmaterial.
 5. The combination of a cannulated dilator and a dilatorretractor as claimed in claim 4 wherein said dilator retractor is madefrom a transparent material.
 6. The combination of a cannulated dilatorand dilator retractor as claimed in claim 3 including an annular clamp,said clamp being dimensioned to fit said dilator retractor and meansincluding a bracket extending from said annular clamp adapted to supportthe dilator retractor to a rigid member.
 7. The combination of acannulated dilator and dilator retractor as claimed in claim 6 whereinsaid clamp is split through a portion thereof to define a gap betweenthe ends adjacent the split, an adjustment for enlarging or decreasingsaid gap and the inner diameter portion surrounding the dilatorretractor for securing said annular clamp to the dilator retractor andincluding means adapted to support the dilator retractor to a rigidmember.
 8. The combination of a cannulated dilator and dilator retractoras claimed in claim 6 including an elongated fixture having a circularcross section and made from a cuttable plastic material, and means tocut said dilator retractor an amount commensurate with the measurementattained by said cannulated retractor and the width of said annularclamp.
 9. The combination of a cannulated dilator and dilator retractoras claimed in claim 8 wherein said elongated fixture includes a seriesof axially spaced grooves spaced a predetermined amount, said dilatorretractor being transparent and fitting over said elongated fixture forthe spaced grooves to be visible wherein the selection of said annulargrooves determines the length of the dilator retractor to be cut. 10.The combination of a cannulated dilator and dilator retractor as claimedin claim 3 including a pusher tool having an elongated circular body, acentral bore having a dimension to complement the outer diameter of saidcannulated dilator, and a bottom surface overlying the end of saiddilator retractor so that when said pusher tool is pushed into the bodycavity the dilator retractor is forced into the body cavity and thecentral bore slides over said cannulated dilator.
 11. The combination ofa cannulated dilator and dilator retractor as claimed in claim 10wherein said pusher tool is integral with said elongated fixture. 12.The combination of a cannulated dilator and dilator retractor, saidcannulated dilator being in the series of the last cannulated dilatorfor enlarging the access hole in the body of a patient, at least one ofsaid cannulated dilators having an elongated body, indicia on saidelongated body indicative of a measurement of depth for measuring thedepth of the access hole, said dilator retractor including a series ofdilator retractors each having different lengths, whereby the dilatorretractor for use in the access hole is selected from said series ofdilator retractors that is commensurate with the measurement of saidcannula(d dilator as obtained from said indicia when inserted into saidaccess hole for defining a working space for performing a medicalprocedure when the cannulated dilator has been removed.
 13. The methodof sizing the length of a cannula to fit the depth of an access holeformed in the body of a patient including the steps of: i. providing acannula that is oversized in length; ii. providing a cannulated dilatorthat is in the last of a series of cannulated dilators used forenlarging the access hole with indicia of a scale for measuring alength; iii. measuring the depth of the access hole by inserting thecannulated dilator obtained in the step of providing a cannulateddilator into the access hole to ascertain the depth; iv. cutting thecannula to the size obtained in the step of measuring before beinginserted into the access hole; and v. inserting the cannula obtained inthe step of cutting into the access hole over the cannulated dilator andremoving the cannulated dilator to define a working space to perform amedical procedure.
 14. The method as claimed in claim 13 including thestep of providing a template made from a cuttable material that isdimensioned to fit into the cannula; i. inserting the template into thecannula; ii. cutting the cannula and template at the length commensuratewith the access hole.
 15. The method as claimed in claim 14 includingthe provision of including markings on said template graduated to ascale commensurate with the scale of the indicia on the cannulateddilator; and the cannula being transparent so that the scale on thefixture is visible.
 16. The method as claimed in claim 14 including aclamp to fit the end of the cannula; cutting in the step of cutting thecannula to a length that includes the width of the clamp.
 17. The methodas claimed in claim 14 including the step of providing a tool forengaging the proximal end of the cannulated dilator and inserting thecannulated dilator by pushing and turning the tool.
 18. The method asclaimed in claim 14 including the step of providing a tool for engagingsaid cannula for pushing said cannula into the access hole.
 19. Themethod of sizing the length of a cannula to fit the depth of an accesshole formed in the body of a patient including the steps of: i.providing a series of different length cannulas; ii. providing acannulated dilator with indicia of a scale for measuring a length; iii.measuring the depth of the access hole by inserting the cannulateddilator into the access hole to ascertain the depth; iv. selecting fromsaid different length cannulas obtained in the step of providing aseries of different length cannulas the length correlating to the lengthobtained in the step of measuring before inserting said selectedcannula; and v. inserting said the cannula obtained in the step ofselecting from said different length cannulas into said access hole fordefining a working chamber for performing the medical procedure.
 20. Thecombination of a cannulated dilator and dilator retractor as claimed inclaim 12 including an annular clamp, said clamp being dimensioned to fitany of said dilator retractor from said series of said dilatorretractors and a bracket extending from said annular clamp adapted tosupport the dilator retractor to a rigid member.
 21. The combination ofa cannulated dilator and dilator retractor as claimed in claim 12wherein each of said cannulated dilator has a proximal end and a toolengagement portion formed thereon, a tool having an engagement portioncomplementing the tool engagement portion of the cannulated dilatoradapted to fit thereon for rotation and applying leverage on saidcannulated dilator for insertion thereof into the body cavity.
 22. Thecombination of a cannulated dilator and dilator retractor, saidcannulated dilator having an elongated body, said cannulated dilator forobtaining the measurement of depth of an access hole formed in a body,said dilator retractor including a series of dilator retractors havingdifferent lengths, whereby the dilator retractor for use in the accesshole is selected from said series of dilator retractors that iscommensurate with the measurement obtained from said cannulated dilatorwhen extended into said access hole.
 23. The combination of a cannulateddilator and dilator retractor as claimed in claim 12 wherein saiddilator retractor is made form a plastic material.
 24. The combinationof a cannulated dilator and dilator retractor as claimed in claim 23wherein said dilator retractr is made form a transparent material.
 25. Asystem for forming an access hole through tissue, comprising: acannulated dilator configured to form and enlarge an access hole throughtissue and into a body cavity; a series of dilator retractors havingdifferent lengths each configured to be inserted over the cannulateddilator such that the cannulated dilator can be removed from the tissueto form a working channel through one of the dilator retractors insertedthereover; wherein a depth of the access hole is measured using acannulated dilator with indicia indicative of a measurement of depth,such that the one of the dilator retractors having a length commensuratewith the depth of the access hole can be selected from the series ofdilator retractors and inserted over the cannulated dilator to form theworking channel.
 26. The system of claim 25, wherein the cannulateddilator includes a beveled end at a distal end thereof and a pluralityof tabs extend from a proximal end thereof.
 27. The system of claim 27,wherein the plurality of tabs extending from the proximal end of thecannulated dilator is configured to engage with a tool for inserting thecannulated dilator through tissue.
 28. The system of claim 25, whereinlengths of each of the dilator retractors are predetermined.
 29. Amethod of forming a working channel through tissue, comprising:inserting a first dilator through tissue to form an access hole;inserting at least one additional dilator over the first dilatorinserted through the tissue, thereby widening the access hole;determining a depth of the access hole using a cannulated dilator;selecting from a series of access instruments having different lengthsan access instrument having a length corresponding to the determineddepth of the access hole; and inserting the access instrument over thefirst dilator and the at least one additional dilator.
 30. The method ofclaim 29, wherein inserting the access instrument includes pushing on aproximal end of the access instrument with a pusher tool to insert theaccess instrument over the dilators.
 31. The method of claim 29, furthercomprising removing the first dilator and the at least one additionaldilator from the tissue, thereby forming a working channel through theaccess instrument.
 32. The method of claim 29, wherein determining thedepth of the access hole comprises using indicia formed on at least oneof the first dilator and the at least one additional dilator.
 33. Themethod of claim 40, further comprising selecting one of a plurality ofpossible lengths of the access instrument based on the depth determinedusing the indicia.
 34. The method of claim 29, wherein the at least oneadditional dilator is cannulated such that the at least one additionaldilator has an inner pathway extending therethrough, and inserting theat least one additional dilator over the first dilator comprisespositioning the first dilator through the inner pathway.
 35. The methodof claim 29, wherein the access instrument defines a pathwaytherethrough, and inserting the access instrument over the first dilatorand the at least one additional dilator results in the first dilator andthe at least one additional dilator extending through the pathway. 36.The method of claim 35, further comprising removing the first dilatorand the at least one additional dilator from the pathway to form aworking channel through the tissue through the pathway defined by theaccess instrument.
 37. A method of forming a working channel throughtissue, comprising: inserting a first dilator through tissue to form anaccess hole; inserting at least one additional dilator over the firstdilator; determining a depth of the access hole using one of the firstdilator and the at least one additional dilator; selecting an accessinstrument from a plurality of access instruments having differentlengths, the access instrument having a length corresponding to thedetermined depth of the access hole; and inserting the access instrumentobtained in the step of selecting from said plurality of differentlength access instruments into said access hole over the at least oneadditional dilator.
 38. The method of claim 37, wherein inserting theaccess instrument includes pushing on a proximal end of the accessinstrument with a pusher tool to insert the access instrument over theat least one additional dilator.
 39. The method of claim 37, whereinselecting the access instrument comprises selecting one of a pluralityof possible lengths of the access instrument based on the determineddepth.
 40. The method of claim 37, further comprising removing the firstdilator and the at least one additional dilator from the tissue, therebyforming a working channel through the access instrument.
 41. The methodof claim 37, wherein determining the depth of the access hole comprisesusing indicia formed on at least one of the first dilator and the atleast one additional dilator.
 42. The method of claim 37, wherein the atleast one additional dilator is cannulated such that the at least oneadditional dilator has an inner pathway extending therethrough, andinserting the at least one additional dilator over the first dilatorcomprises positioning the first dilator through the inner pathway. 43.The method of claim 37, wherein the access instrument defines a pathwaytherethrough, and inserting the access instrument over the at least oneadditional dilator results in the first dilator and the at least oneadditional dilator extending through the pathway.
 44. The method ofclaim 43, further comprising removing the first dilator and the at leastone additional dilator from the pathway to form a working channelthrough the tissue through the pathway defined by the access instrument.45. A system for forming an access hole through tissue, comprising: aplurality of dilators of increasing diameter configured to form andenlarge an access hole through tissue and into a body cavity viasequential dilation; and a plurality of access instruments of differinglengths, wherein a depth of the access hole is measured via indicia onat least one of the dilators such that a one of the access instrumentshaving a length commensurate with the measured depth of the access holecan be selected from the plurality of access instruments and insertedover the dilators to form a working channel.
 46. The system of claim 45,wherein the lengths of each of the access instruments is predetermined.47. The system of claim 45, wherein the one of the access instrumentsdefines a pathway therethrough, the pathway forming the working channel.48. The system of claim 45, wherein at least one of the dilators has abeveled end.
 49. A method of forming a working channel through tissue,comprising: inserting a first dilator through tissue to form an accesshole; inserting at least one additional dilator over the first dilator;determining a depth of the access hole using indicia of a scale formeasuring a length formed on at least one of the first dilator and theat least one additional dilator; selecting a retractor from a pluralityof retractors each having a different length, the length of the selectedretractor being commensurate with the determined depth of the accesshole; and inserting the retractor over the at least one additionaldilator.
 50. The method of claim 49, further comprising removing thefirst dilator and the at least one additional dilator from the tissue,thereby forming a working channel through the retractor.
 51. The methodof claim 49, wherein selecting the retractor comprises selecting one ofa plurality of possible lengths of the retractor based on the determineddepth.
 52. The method of claim 49, wherein the at least one additionaldilator is cannulated such that the at least one additional dilator hasan inner pathway extending therethrough, and inserting the at least oneadditional dilator over the first dilator comprises positioning thefirst dilator through the inner pathway.